In this paper we study a low frequency model for acoustic propagation in a 2D flow duct.For some Mach profile flow,we are able to give a well-posedness theorem.Its proof relies on a quasi-explicit expression of the so...In this paper we study a low frequency model for acoustic propagation in a 2D flow duct.For some Mach profile flow,we are able to give a well-posedness theorem.Its proof relies on a quasi-explicit expression of the solution which provides us an efficient numerical method.We give and comment numerical results for particular linear,tangent and quadratic profiles.Finally,we give a numerical validation of our asymptotic model.展开更多
嵌入式大气数据传感系统(Flush Air Data Sensing System,FADS)通过在飞行器表面特定区域布置测压孔测量来流压力,根据建立的气动模型反推得到飞行参数(攻角、侧滑角、马赫数、静压及动压等)。利用在尖楔前体表面三维区中分布测压孔的方...嵌入式大气数据传感系统(Flush Air Data Sensing System,FADS)通过在飞行器表面特定区域布置测压孔测量来流压力,根据建立的气动模型反推得到飞行参数(攻角、侧滑角、马赫数、静压及动压等)。利用在尖楔前体表面三维区中分布测压孔的方法,根据三维区中的流动特征和压力分布规律,建立压力分布与飞行参数之间的关系。试验结果表明,基于三维区理论的FADS系统得到的马赫数误差在5%左右,精度较高。展开更多
Based on the morphology of Luoshan-Hankou reach at the middle Yangtze River, the one-dimensional, unsteady flow and sediment transport numerical model was adopted to study the generalized cha nnel equilibrium profile...Based on the morphology of Luoshan-Hankou reach at the middle Yangtze River, the one-dimensional, unsteady flow and sediment transport numerical model was adopted to study the generalized cha nnel equilibrium profile. The variation of the longitudinal equilibrium profile, and the r elation with the condition of the inflow water and sediment from the upper reach were analyzed. Meanwhile, the numerical simulation results were compared with t he corresponding theoretical results. Finally, the equilibrium longitudinal slop e variations and its impact on flood control were analyzed after the sediment tr ansport process has changed.展开更多
文摘In this paper we study a low frequency model for acoustic propagation in a 2D flow duct.For some Mach profile flow,we are able to give a well-posedness theorem.Its proof relies on a quasi-explicit expression of the solution which provides us an efficient numerical method.We give and comment numerical results for particular linear,tangent and quadratic profiles.Finally,we give a numerical validation of our asymptotic model.
文摘嵌入式大气数据传感系统(Flush Air Data Sensing System,FADS)通过在飞行器表面特定区域布置测压孔测量来流压力,根据建立的气动模型反推得到飞行参数(攻角、侧滑角、马赫数、静压及动压等)。利用在尖楔前体表面三维区中分布测压孔的方法,根据三维区中的流动特征和压力分布规律,建立压力分布与飞行参数之间的关系。试验结果表明,基于三维区理论的FADS系统得到的马赫数误差在5%左右,精度较高。
基金Project supported by the National Natural Science Foundation of China (Grant No:59890200) the Ministry of Water Resources of
文摘Based on the morphology of Luoshan-Hankou reach at the middle Yangtze River, the one-dimensional, unsteady flow and sediment transport numerical model was adopted to study the generalized cha nnel equilibrium profile. The variation of the longitudinal equilibrium profile, and the r elation with the condition of the inflow water and sediment from the upper reach were analyzed. Meanwhile, the numerical simulation results were compared with t he corresponding theoretical results. Finally, the equilibrium longitudinal slop e variations and its impact on flood control were analyzed after the sediment tr ansport process has changed.
